Text Diff Checker
Enter text on both sides and click Compare to see the differences here.
Compare two blocks of text and see what's added, removed, or changed | 100% Private
Uses a proper longest common subsequence algorithm for accurate, minimal diffs — not a naive line match.
Switch between line-by-line comparison for whole documents and word-by-word for fine-grained edits.
Optionally ignore whitespace-only or case-only differences so you only see meaningful changes.
Added text is highlighted green, removed text is struck through in red, unchanged text stays plain.
Copy the full diff result to your clipboard instantly with a single click.
All comparison happens in your browser using JavaScript — nothing is ever uploaded to a server.
Whether you're reviewing an edited document, checking a code change, or spotting differences between two versions of a file, a reliable diff tool saves you from manually scanning line by line. This tool compares two blocks of text and highlights exactly what changed using the same core algorithm that powers most version-control diff tools.
The tool splits both texts into tokens — either lines or words — and finds the longest common subsequence (LCS) between the two token lists: the largest set of tokens that appear in both texts in the same relative order. Anything in the original text that isn't part of that shared sequence is marked as removed, and anything in the changed text that isn't part of it is marked as added. This is the same principle used by tools like `diff` and Git.
Line mode is best for comparing whole paragraphs, code files, or documents where you want to know which lines changed. Word mode digs inside each line to show precisely which words were added, removed, or replaced — ideal for proofreading or reviewing small edits to a sentence.
It splits both texts into lines or words and runs a longest common subsequence (LCS) algorithm to find the largest set of pieces that appear in the same order in both texts. Everything outside that common sequence is marked as added or removed.
No. The comparison runs entirely in JavaScript inside your browser tab. Your text is never sent to any server, logged, or stored anywhere.
Line mode compares the texts line by line, so a whole line is marked as added or removed if it changed. Word mode compares word by word within the text, which is more precise for spotting small edits inside a sentence or paragraph.
'Ignore whitespace' collapses extra spaces and trims lines before comparing, so formatting-only differences aren't flagged. 'Ignore case' treats uppercase and lowercase letters as equal. Both only affect how matches are detected — your original text is always shown unchanged in the result.
Yes, though very large texts (many thousands of lines) may take a moment to process since the LCS algorithm's memory use grows with the size of both inputs. For typical documents, code snippets, or paragraphs, comparison is instant.